The procurement and processing of human bone for transplantation has not changed significantly since the 1950s. It remains a complicated task which requires the coordinated efforts of several groups including the donor's family, the hospital staff, the local procurement group, the blood specimen processing laboratory, the bone processing laboratory, the transplant patient, and the transplant team.
A prime consideration is minimization of the risk of transferring potentially harmful diseases to tissue recipients. Viruses and bacteria can be transmitted by the bone as well as the marrow. See Kakaiya et al., "Tissue transplant-transmitted infections," Transfusion 31 (3) 1277-284, 1991; Shutkin, "Homologous-serum hepatitis following use of refrigerated bonebank bones, report of a case," J. Bone Joint Surg. 36 -A160, 1954. Transmission of human im nodeficiency virus (HIV) via bone as well as bone marrow has also been reported. "Transmission of HIV through bone transplantation case report and public health recommendations" Novbid. Mortal Weekly Rep., 37:597-599, 1988. Furlini et al., "Antibody response to human immunodeficiency virus after infected bone marrow transplant," Eur. J. Clin. Microbiol. Infect Dis, 7(5)554-665, 1988. Furthermore, HIV has been cultured from fresh as well as refrigerated bone and freeze-dried bone. Buck et al. "Human immunodeficiency virus cultured from bone. Implications for transplantation." Clin. Ortho., 251:249-253, 1990. Protection of the bone processing laboratory technician is another consideration which has become more pressing in recent years because of the possibility of HIV and hepatitis B transmission.
Current bone procurement and processing procedures have been designed to minimize these risks. Typically, the hospital and a local procurement agency first review hospital records regarding the potential donor's serology and disease status to determine if the donor falls within acceptable medical criteria. If all is in order and the required consents have been obtained, technicians from the local procurement agency begin collecting blood samples and removing specified organs, tissues and bones within hours of the donor's death. During the procurement process, the bones may be dipped in an antibiotic cocktail (usually a bacitracin/polyrnixin solution). Typically, the bones are then chilled on ice or frozen, and shipped to a processing laboratory.
At the processing laboratory the blood samples may be analyzed for a variety of known infectious agents including:
Human immunodeficiency virus (HIV-1) PA1 Human immunodeficiency virus (HIV-2) PA1 Human T cell lymphotropic virus (HTLV-1) PA1 Hepatitis B PA1 Hepatitis C PA1 Cytomegalic virus (CMV) PA1 Treponema pallidum (syphilis).
Typically, technicians proceed to thaw the bone and place the pieces in antibiotic cocktail. They then clean the bones with sterile water. After debridement of external fat and tissue with sterile water, the bones may be cut into specific sizes. Technicians remove the marrow using sterile water to which hydrogen peroxide may have been added to further defat and whiten the bone. Finally, if desired, the bone may be incubated in ethanol for at least one hour. Select bone pieces are packaged in such a way as to preserve sterility and biologic potential. A popular and practical method with processing laboratories is to lyophilize the bone to dryness, size, and package the select bone pieces. Other methods include cryopreservation and fresh freezing. To ensure sterility at the end of the process, samples from the packages are cultured for microorganisms.
The combination of donor screening and antibiotic treatments currently employed during processing reduces the risk of transmission of known vital contaminants and a variety of bacteria. Current methods however offer no prophylactic protection from viruses, select bacteria, and fungi which are common flora in humans and in a hospital environment. First, screening tests are not foolproof. Although the sensitivity and specificity of screening tests are high, false negatives may result from, for example, low antibody or antigen levels (e.g., recent infection or immunodeficiency) or even technician error. Furthermore screening tests may be useful only to identify known infectious agents. Second, antibiotic cocktails currently in use do not readily kill all types of bacteria. For example, the polymixin/bacitracin solution commonly used does not inactivate Proteus species. Furthermore, antibiotic cocktails have no significant effect on viruses or fungi.
While cleanliness of the bone is believed to be an important factor in avoiding transplant-related infection and antigenicity, it is difficult to clean bone pieces effectively by the conventional methods. Cells and debris harbor infectious agents and may provoke antigenic response.
The present invention provides a method of processing bone for transplantation having prophylactic protection from a wide range of infectious agents which are not readily inactivated or screened for by current methods. In particular, the present invention offers a simple method of not only decontaminating bone from a wide range of infectious agents, but also of effectively cleaning the bone so as to eliminate any cells or debris which may harbor such infectious agents.
The present invention also provides a method for cleaning and decontaminating human bone for transplantation which is safe for the laboratory technician.
These and other objects, features and advantages of the invention will become apparent after review of the following detailed description of the disclosed embodiments and the appended claims.